The Notacanthiformes are an order of deep-sea ray-finned fishes, consisting of the families Halosauridae and Notacanthidae (spiny eels).
The order is of relatively recent vintage; Fishes of the World lists it as the suborder Notacanthoidei of Albuliformes. The notacanthiforms are much more eel-like than the albuliforms; for instance, the caudal fin has disappeared.